1. Field of the Invention
The present invention relates to a manufacturing method for a semiconductor apparatus, and in detail, the present invention particularly relates to such a manufacturing method for a semiconductor apparatus, wherein a micro wiring pattern is formed.
2. Description of the Related Art
In recent years, the miniaturization of a wiring pattern has been quickly advanced in order to improve the degree of integration and the property of an LSI. The techniques for miniaturizing a gate length in order to improve the property of a transistor and for opening a contact hole smaller than that of a conventional contact hole in order to improve the degree of integration have been strongly requested. It is well known that a limit resolution (R) in an optical lithography process to determine the minimum size of the LSI is represented by the following equation (1):R=k×λ/NA  (1)
In this case, λ is a wave-length of a light source, NA is the numerical aperture in a projection lens, and k is a constant having a value of about 0.5.
That is, in order to attain the lithography process having a resolution higher than that of the conventional one, it is desirable to select a light source having a shorter wave length. Because of this reason, a photolithography machine, which uses a krypton fluorine (KrF) excimer laser having a wave-length of 248 nm as a light source, is used in a field of manufacturing an high technology device. However, NA of a current exposing apparatus is 0.68 at its maximum. Thus, even the latest KrF excimer laser photolithography machine has only a resolution of about 0.18 μm. However, the resolution derived from the equation (1) is applied to a banded pattern typically referred to as a line and space. Then, the resolution of the contact hole pattern has a limit of about 0.22 μm.
On the other hand, a technique for opening a micro contact hole having a diameter of 0.15 μm is requested in a device of 0.13 μm generation. This is the size that can not be easily attained even by using an argon fluorine (ArF) excimer laser photolithography machine, which is expected as a next generation photolithography machine using a light source having a wave length of 193 nm.
As one method of solving this problem, a technique for carrying out an etching process so as to give a taper to a side wall of a hole 112 formed on a film 111 to be processed by using a resist mask 121 is known and thereby finishing it to a desired hole diameter at a bottom 112b of the hole 112, as shown in FIG. 3.
However, as shown in FIG. 4, in the above-mentioned conventional method, even if a desired hole diameter (a hole diameter on design) Db is obtained at the bottom 112b of the hole 112, a diameter Dt at an upper end (aperture) 112t of the hole 112 becomes greater than the desired size (a size on the design). This results in a problem that a sufficient matching margin can not be obtained at a later lithography process. For example, this has a problem that a distance d from a wiring 13I placed adjacently to the hole 112 is made narrower.
The present invention is a manufacturing method for a semiconductor apparatus proposed in order to solve the above-mentioned problems.